When I turned on the shower, water was flowing out of the tub.spout I replaced the divertor valve and seat. After installing these new parts, the problem still exists. What could the other probable causes why water is still coming from the tub spout.

Welcome Gearshift:
It is possible the new diverter valve and seat are not completely in line. You could try putting your finger up in the spout and pushing the diverter while you pull up on the knob, to make it close off better. Diverter valves are designed to easily drop out when the pressure is turned off as a backflow preventer. Some times the are just built too loose.
Glenn